1. Field of the Invention
This invention relates to motors that provide rotary motion. More particularly, one embodiment of the present invention relates to a motor which is constructed from materials that can be used in all classes of medical imaging equipment and that generates precise, high torque, backlash-free rotary motion without using electricity.
2. Description of Prior Art
Noninvasive, diagnostic imaging techniques, such as ultrasound, x-ray and magnetic resonance imaging (MRI) are widely used in medicine. They are used to produce cross-sectional images of a patient's organs and other internal body structures.
MRI typically involves the patient lying inside a large, hollow cylinder containing a strong electromagnet, which generates a strong and uniform magnetic field that causes the electrons in a patient's body to spin in a uniform and predictable manner. The MRI equipment can then manipulate the spinning electrons and use the resulting information to generate an image of the inside of a patient's body.
However, difficulties are encountered in obtaining accurate images when disruptions and deflections in the magnetic field are experienced due to the presence in the field of materials that produce a magnetic field and/or are susceptible to producing their own magnetic fields when placed within an external magnetic field.
One source of magnetic field distortion can be equipment such as motors that are in the vicinity of the MRI machine. Motors are generally formed with materials that produce a magnetic field. Examples of such materials that are commonly used in motors include iron and brass. Thus, when placed in the field generated by the MRI machine, the motors can cause artifacts in the image of the patient's body.
Other forms of medical imaging (e.g., x-ray and ultrasound imagers) are also seen to have similar problems of distortions in their output images due to the presence of motors in the vicinity of the imaging equipment.
Prior attempts to provide a motor that can be used in such imaging environments have involved the use of piezoelectric elements to provide the motor's power. See U.S. Pat. Nos. 5,233,257 and 6,274,965.
Despite these efforts, there still exists a need for improved motors that can be placed near medical imaging equipment with minimal risk of creating artifacts. There is a related need for a motor that does not produce a magnetic field. There is yet another need for a motor that has a low susceptibility of being induced to produce a magnetic field. Additionally, there is a need for a rotary motor of the type that is not powered by electricity.
3. Objects and Advantages
There has been summarized above, rather broadly, the prior art that is related to the present invention in order that the context of the present invention may be better understood and appreciated. In this regard, it is instructive to also consider the objects and advantages of the present invention.
It is an object of the present invention to provide a rotary motor that can be used for medical applications which require the motor to be located in or in close proximity to medical imaging equipment.
It is another object of the present invention to provide a rotary motor that can be used in a surgical environment.
It is yet another object of the present invention to provide a motor that can provide precise, high torque, backlash-free rotary motion.
It is still another object of the present invention to provide a rotary motor that does not utilize electrical power or electrical components for operation.
It is a further object of the present invention to provide a precise rotary motor whose motion can be monitored by sensors located at a site that is distant from the location of the motor itself.
It is an object of the present invention to provide a rotary motor that can be powered by other than electrical means.
These and other objects and advantages of the present invention will become readily apparent as the invention is better understood by reference to the accompanying summary, drawings and the detailed description that follows.